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CN-119553267-B - Preparation method of double-layer protective coating with self-repairing characteristic

CN119553267BCN 119553267 BCN119553267 BCN 119553267BCN-119553267-B

Abstract

The invention discloses a preparation method of a double-layer protective coating with self-repairing characteristics, which aims to solve the problems that the bonding strength of a high-entropy alloy coating and a matrix is low, and long-term service stability is difficult to maintain. The preparation method comprises the steps of firstly, preprocessing a matrix, secondly, calculating average atomic radius difference, VEC, mixed entropy and mixed enthalpy of a high-entropy alloy multi-element system, mixing and ball milling corresponding single-substance powder, thirdly, performing cladding deposition on the mixed metal powder by adopting a high-energy beam deposition process, fourthly, polishing, cleaning a high-entropy alloy coating, and fifthly, forming an oxide layer or a nitride layer on the high-entropy alloy coating in situ by adopting an oxidation process or a nitridation process. The double-layer protective coating with the self-repairing characteristic has the double-layer protection of the high-entropy alloy coating and the in-situ oxidation/nitridation layer with excellent corrosion resistance, wherein the high-entropy alloy coating is diluted by a matrix in design to form a stable intermetallic compound, and the matching property of the coating and the matrix is improved.

Inventors

  • CUI XIUFANG
  • LIU CHANGHAO
  • JIN GUO
  • LI CHENGTAO
  • WU DI
  • QI MENG
  • ZHAO JIAXIN
  • LI SHIYANG

Assignees

  • 哈尔滨工程大学

Dates

Publication Date
20260512
Application Date
20241128

Claims (8)

  1. 1. The preparation method of the double-layer protective coating with the self-repairing characteristic is characterized by comprising the following steps of: 1. Sequentially polishing, polishing and cleaning the surface of the matrix to obtain a pretreated matrix; 2. Analyzing metal elements in a matrix, selecting one element with the metal element content not lower than 30% or the element with the maximum metal element content in the matrix as an additive element, selecting 2-6 elements from easily-oxidized elements as alloy elements, forming a high-entropy alloy multi-element system by the additive elements and the alloy elements, and calculating average atomic radius differences delta, VEC, delta Smix and delta Hmix of the high-entropy alloy multi-element system to ensure that the average atomic radius difference delta of the high-entropy alloy multi-element system is less than or equal to 15%,6.7 (e/a) is less than or equal to VEC and less than or equal to 8 (e/a), 12J/(mol.K) is less than or equal to 17.5J/(mol.K) and-22 kJ/mol is less than or equal to delta Hmix is less than or equal to 7kJ/mol; putting the corresponding single-substance powder of the additive element and the alloy element into a high-energy ball mill together for ball milling treatment to obtain mixed powder; 3. coating the mixed powder on the surface of the pretreated substrate, and carrying out cladding deposition on the mixed metal powder by adopting a high-energy beam deposition process to form a high-entropy alloy coating; 4. sequentially polishing, polishing and cleaning the high-entropy alloy coating to obtain a substrate with the high-entropy alloy coating; 5. An oxidation layer is formed on the high-entropy alloy coating in situ by adopting an oxidation process, so that a double-layer protective coating with self-repairing characteristics is obtained; wherein the easily oxidized elements in the second step are Cr, fe, al, si, co, ni, zr and Ti; the oxidation process in the fifth step is a high-temperature oxidation process or a micro-arc oxidation process, wherein the high-temperature oxidation process is to put a substrate with a high-entropy alloy coating into a high-temperature furnace, and perform high-temperature oxidation treatment at 600-800 ℃ in air atmosphere or oxygen atmosphere.
  2. 2. The method for preparing a double-layer protective coating with self-repairing characteristics according to claim 1, wherein the calculation formula of the average atomic radius difference delta of the high-entropy alloy multi-element system in the second step is as follows: wherein C i is the mole percent of each element in the high-entropy alloy multi-element system, r i is the atomic radius, Is the average atomic radius of all elements in the high-entropy alloy multielement system.
  3. 3. The method for preparing a double-layer protective coating with self-repairing characteristics according to claim 1, wherein the calculation formula of the VEC of the high-entropy alloy multi-element system in the second step is as follows: Wherein C i is the mole percent of each element in the high-entropy alloy multi-element system, and (VEC) i is the valence electron concentration of each element in the high-entropy alloy multi-element system.
  4. 4. The method for preparing a double-layer protective coating with self-repairing characteristics according to claim 1, wherein the particle size of the mixed metal powder in the second step is 45-80 μm.
  5. 5. The method for preparing the double-layer protective coating with the self-repairing characteristic according to claim 1, wherein the laser power is controlled to be 1000-1500W in the high-energy beam deposition process in the third step.
  6. 6. The method for preparing the double-layer protective coating with the self-repairing characteristic, which is characterized in that the deposition rate is controlled to be 10-15 mm/s in the high-energy beam deposition process in the step three.
  7. 7. The method for preparing the double-layer protective coating with the self-repairing characteristic according to claim 1, wherein the thickness of the high-entropy alloy coating in the third step is 400-800 μm.
  8. 8. The method for preparing a double-layer protective coating with self-repairing characteristics according to claim 1, wherein the thickness of the oxide layer in the fifth step is 20-50 μm.

Description

Preparation method of double-layer protective coating with self-repairing characteristic Technical Field The invention belongs to the technical field of composite coatings, and particularly relates to a preparation method of a double-layer protective coating with self-repairing characteristics. Background The surface technology has great application in improving the surface performance of the part, and the high-entropy alloy coating has four effects, so that the high-entropy alloy coating has wider application prospect compared with the traditional protective coating, for example, the mature AlCoCrFeNi eutectic high-entropy coating has been primarily applied to tools such as cutters. The excellent corrosion resistance and other properties of the high-entropy alloy coating are applied to various fields and parts, but in application exploration, the problems of peeling and the like caused by poor coating formability, complex phase, lower bonding strength and the like exist due to the difference of the thermal properties of the coating and the substrate, and long-time service stability is difficult to maintain under increasingly severe working environments, so that the long-time service properties of the coating are required to be optimized through structural design on the premise of ensuring good bonding of the substrate and the high-entropy alloy coating. Disclosure of Invention The invention aims to solve the problems that the bonding strength of a high-entropy alloy coating and a matrix is low and long-term service stability is difficult to maintain, and provides a preparation method of a double-layer protective coating with self-repairing characteristics. The preparation method of the double-layer protective coating with the self-repairing characteristic is realized according to the following steps: 1. Sequentially polishing, polishing and cleaning the surface of the matrix to obtain a pretreated matrix; 2. Analyzing metal elements in a matrix, selecting one element with the metal element content not lower than 30% or the element with the maximum metal element content in the matrix as an additive element, selecting 2-6 elements from the elements easy to oxidize/nitride as alloy elements, forming a high-entropy alloy multi-element system by the additive elements and the alloy elements, and then calculating the average atomic radius difference delta, VEC (valence electron concentration), delta Smix (mixed entropy) and delta Hmix (mixed enthalpy) of the high-entropy alloy multi-element system (comprising the matrix elements and the elements easy to oxidize/nitride), so that the average atomic radius difference delta of the high-entropy alloy multi-element system is not more than 15%,6.7 (e/a) not more than VEC not more than 8 (e/a), 12J/(mol.K) not more than 17.5J/(mol.K) and-22 kJ/mol not more than delta Hmix not more than 7kJ/mol; putting the corresponding single-substance powder of the additive element and the alloy element into a high-energy ball mill together for ball milling treatment to obtain mixed powder; 3. coating the mixed powder on the surface of the pretreated substrate, and carrying out cladding deposition on the mixed metal powder by adopting a high-energy beam deposition process to form a high-entropy alloy coating; 4. sequentially polishing, polishing and cleaning the high-entropy alloy coating to obtain a substrate with the high-entropy alloy coating; 5. an oxidation process is adopted to form an oxidation layer on the high-entropy alloy coating in situ, or a nitridation process is adopted to form a nitridation layer in situ, so that a double-layer protective coating with self-repairing characteristics is obtained; wherein the elements easy to oxidize/nitridize in the second step are Cr, fe, al, si, co, ni, zr and Ti; the oxidation process in the fifth step is a high-temperature oxidation process or a micro-arc oxidation process, and the nitriding process is an ionic nitriding or carbonitriding process. The middle and bottom layers of the double-layer protective coating with the self-repairing characteristic are high-entropy alloy coatings, and the surface layers are in-situ oxidation/nitridation layers. The high-entropy alloy coating has excellent corrosion resistance and high temperature resistance, the selected elements are all easily oxidized/nitrided elements, the internal structure of the coating is intermetallic compound, and the in-situ oxidation/nitridation layer is formed by pre-oxidation/nitridation catalysis on the surface of the high-entropy alloy coating. The double-layer protective coating with the self-repairing characteristic has the double-layer protection of the high-entropy alloy coating and the in-situ oxidation/nitridation layer with excellent corrosion resistance, wherein the high-entropy alloy coating is diluted by a matrix in design to form a stable intermetallic compound, and the problem of insufficient matching between the coating and the matrix is solved. Meanwh